Most people do not realize how easy it is to get into a typical garage. Even worse, once a burglar makes it into your garage, they then have tools and concealment and can finish breaking into your home at leisure. Any doors from your garage to your home, or man doors to the outside, should be exterior grade metal clad or solid wood doors equipped with a quality deadbolt lock and upgraded hardware, as discussed elsewhere on CrimeRepellent.com. You should also keep any valuables in a more secure area inside your home. Power tools or other targets of theft that are normally stored in the garage should be in a locked container like a sturdy cabinet or toolbox. The container itself should be fastened in place or of sufficient weight to make transport difficult, and out of sight when the garage door is open if possible.
The simplest way criminals make unauthorized entry to a garage requires only a door stop and a wire coat hanger. The door stop is used as a wedge to create a gap at the top of the garage near the center, and the coat hanger is bent in such a fashion to use to reach in and pull the manual release on your garage door opener. This type of attack is easily defeated by using a sturdy plastic zip tie to secure the manual release latch in such a fashion that pulling the release cord has no effect. A minute or two of examining the mechanism will likely be all that is needed to determine where to apply the zip tie. Should you need to use the manual release, it is a simple matter to cut the zip tie if you are inside the garage, but quite difficult to do from outside. If you are unable to secure your manual release with a zip tie, you may wish to remove the release pull cord entirely, though this will make it more difficult to open the garage door in case the opener, or your power, fails.
If the garage is going to remain closed for any duration of time, such as a garage only used for storage or during away from home trips, look for a manual latch or a location you can apply a bolt or a padlock to lock the garage door closed from the inside.
One final area of concern is to clear any hiding spaces close to the garage door, such as trash cans left outside or bushes growing too close. This will make it more difficult for someone to sneak in behind you when you enter or depart the garage yourself. Being alert to this possibility and watching for criminals attempting it is even more important than any physical security measures you could take.